jTherm-Pro: Multi Purpose Dual-Probe Programmable Temperature Monitor

Finally got my latest project in a nice enclosure.

  • 2200mAh LiPo battery for 18 hours of runtime
  • Mini-USB input for Power/Charge
  • Accepts any K-Type thermocouple Probe with “Mini” jacks

Software features:

  • Send data to xively.com every 30 seconds (xively’s default graphs are perfect for this.)
  • iOS app for viewing temperature data and setting alert trigger points (nearly complete)
  • Send alerts to Twilio for SMS notifications.

If you love to BBQ/Grill/Homebrew this is a great little project.

Love it!

This is fantastic. I plan on creating the same, but a bit simpler, to monitor/log fermentation temp vs ambient temp.

Any chance you can post a parts list? Mainly the temp sensor stuff.


Is there a hole for the display, or is it just an un-frosted area of the plastic?

No hole yet, the display is under the plastic. Not as polished that way, but it does protect it. The Sparkfun enclosure seemed like a decent size, though I had to get a little bit creative to fit everything in where it could be accessed. I’d love to get everything on a single board with an imp002.

I am having a little trouble figuring out how to send multiple values in the HTTP request body to the agent from my iPhone app. I want to set trigger points that the imp can check and send a Twilio SMS if any of the temps go over or under. I’m not sure if I can send something like: value=0,240,0,200. I am trying to extend the InputPort class and I think I want to send it an array. Sending one value is easy, but I’m not quite getting how to do multiples.

Thanks to @beardedinventor, I have my iPhone app successfully sending high and low trigger values to the imp for each temperature probe. I have the agent and device code on github. If anyone wants to offer feedback on how to write the code more efficiently, I’m sure there is a lot of room for improvement…but it does work!


Nice! I will say this about thermocouples, they usually have a ±2 degree accuracy, though that is at higher temps. At fermentation temps you should be much closer, but I know you’ll want to be really precise for that. I would calibrate whatever probes you use with a thermometer that you trust, like a Therma-Pen if you want to be spot on. I used the Adafruit MAX31855 breakout board, and then got K-Type thermocouple mini-jacks. I think I got them from Mouser.com. Thermoworks.com has lots of K-type t-couples. They aren’t cheap, but they are nice. They have some beverage probes that should work nicely for fermenters. I’m trying to get the project website updated, so check that, and I’ll try to provide all the details that I can. I am also working on a custom PCB for this project, in the hopes that it could be available as a kit.


If you want to go simple, get an Imp and an April breakout, the Adafruit MAX31855 breakout, and a probe from thermoworks.com that is good for liquids. You need 5 jumpers to connect the 31855 to the imp and connect your t-couple. Get the code from my github account, modify it for you needs, set up a xively.com account and start pushing data.

What about monitoring your mash temps? One of these days I’m going to hook this thing up to my Blichmann kettles.

Thanks for the response.

Mid/long term plan is to monitor mash temp and control my heatstick via a relay and some PID logic, but I need a recirc pump first. I don’t need a display on the device itself, I’ll just have a laptop nearby to monitor & set the temperature, etc.

I have to say, after spending lots of money and building a nice recirc system… triple claps, pump ect… I’d probably just go back to using a cooler, its simple and the results are good.

… but most of the fun I had brewing was actually setting things up and enjoying the process, so I guess its not about simple. :slight_smile:

I need to fire my system up and use the probes on it soon…

I hear ya about the process - can’t count the number of hours I spent overclocking my PC… then proceeded to do nothing requiring the extra power.

I’ve just got a simple BIAB setup, so nothing too fancy.

Latest prototype of the jTherm:

The Adafruit Arduino enclosure is nice with the LCD window, and I am using the barrel jack connector and the USB connection slots in the base. Not happy with the extra space around the mini-B jack though. Sugru maybe?

You can’t see the two thermocouple breakouts under the April. I am mounting everything in layers on the solderable breadboard.

It works fine, but I am still not quite happy with the layout. Issues that I still want to work out:

  1. Only one pin remains on the April, and I want to read the LiPo charging status to the LCD. Need to sort out that logic.
  2. Not happy with all the space around the Mini-B power/charge port.
  3. Power switch is ok, but it would be nice to have a small lighted rocker mounted somewhere. Not much space above the LCD.

Ideas anyone?

Inside the latest prototype with Adafruit components. Not shown is the 5.0V boost convertor from Pololu. It is down under the LiPo charger. The serial LCD backpacks work much better with 5V.

I’ve got the MAX31855 breakouts covered in Sugru, in an attempt to insulate them from heat inside the enclosure. It does work better that mounting them near the other components, but still room for improvement.

I used both of the original openings for the Arduino. You can charge/power the device with a barrel jack plug or Mini USB.

I modified an Adafruit perf board to attach where the Arduino would. Works nicely.